Output from Wolfram language in Python

Question

I have a Python program which will run a script in the Wolfram language and then return to the main program. Is it possible to return values/variables to the main program?

This is the code in Python running the Wolfram language code:

os.system('wolfram  -script file.wl')

Then in file.wl, for example, I can run a command such as 1+1, which will give me an output of 2.

Can I then use this value 2 in the rest of my Python program?

e.g. print (ans)

Answer 1

The os.system command will not help you, because it does not return/provide the output of the command executed. What you want is to have a look at this answer on Stack Overflow to see how you can get the stdout of a command into a Python variable.

In your Mathematica script you simply Print the result and with the given method in the other answer you will fetch this result to your Python script.

Here a working example. I don't have a Raspberry Pi and therefore, the command is still good old MathematicaScript for me.

1. Create a Mathematica script file which I called test.m here with the following content.

   Print[1+1]
   

2. Create a runScript.py with the following content. Here I'm using the Python 2.7 function subprocess.check_output:

   import subprocess
   
   output = subprocess.check_output(['MathematicaScript', '-script', 'test.m'])
   print output
   

3. Run the script with something like /usr/bin/python runScript.py.